The present invention relates generally to apparatus for the production of casting molds and more particularly to apparatus wherein material for forming a casting mold is compressed within molding flasks containing the material.
In mold forming equipment of the type to which the present invention relates, substantial increases in the sizes of the molding flasks which are utilized as a result of mechanization or automation of plants within which such equipment is operated has effected a considerable increase in the degree of deformation or distortion which occurs in the walls of the molding flask during the compression therein of the mold forming material or molding sand. Plastic or elastic deformation of the molding flasks will be subjected to added increase during compression by the introduction of high pressure molding. The elastic deformation of the molding flasks during compression is further increased during compression as a result of the application of new filling methods of the molding sands in the molding flasks, the profiled sand filling being stripped off before the compression on the top side in adaptation to the pattern volume.
The elastic deformation which occurs in the walls of the molding flask tends to attain a maximum degree of deformation during compression of the molding sand particularly when the patterns which are utilized in forming the casting molds have a relatively large volume. The deformation of the molding flask produces the additional disadvantage in that it enhances breakoff of mold balls and mold edges during separation of the casting mold parts from the pattern device.
Furthermore, offset of the castings tends to be increased and the accuracy of the dimensions or size of the castings is also impaired as a result of the deformation which may occur in the molding flasks.
Heretofore, the most effective manner for preventing elastic deformation of molding flasks has involved the utilization of stiffening means consisting of traverses or stiffening devices which are installed to extend across the mold flask. The traverses, however, produce the significant disadvantage that they reduce the molding flask inner space which is available for utilization and that the uniformity of compression of the casting mold parts is also impaired. Since such traverses also affect the disassembly of the casting moles in that such disassembly is rendered more difficult, they are no longer utilized in molding and casting plants.
Other known approaches have involved attempts to achieve stiffening of the molding flasks by increasing the profiles of the molding flasks taken in the bending direction and by designing them as hollow bodies. However, experience has shown that the desired stiffening effects for molding flasks cannot be achieved by measures such as these.
Accordingly, there exists a need for providing support for molding flasks utilized in equipment for forming casting molds.
The present invention is directed toward achievement of appropriate support and bracing for molding flasks utilized in mold forming equipment during the compression of casting mold parts.